1
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Guarracini F, Tritto M, Di Monaco A, Mariani MV, Gasperetti A, Compagnucci P, Muser D, Preda A, Mazzone P, Themistoclakis S, Carbucicchio C. Stereotactic Arrhythmia Radioablation Treatment of Ventricular Tachycardia: Current Technology and Evolving Indications. J Cardiovasc Dev Dis 2023; 10:jcdd10040172. [PMID: 37103051 PMCID: PMC10143260 DOI: 10.3390/jcdd10040172] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/21/2023] [Revised: 04/12/2023] [Accepted: 04/15/2023] [Indexed: 04/28/2023] Open
Abstract
Ventricular tachycardia in patients with structural heart disease is a significant cause of morbidity and mortality. According to current guidelines, cardioverter defibrillator implantation, antiarrhythmic drugs, and catheter ablation are established therapies in the management of ventricular arrhythmias but their efficacy is limited in some cases. Sustained ventricular tachycardia can be terminated by cardioverter-defibrillator therapies although shocks in particular have been demonstrated to increase mortality and worsen patients' quality of life. Antiarrhythmic drugs have important side effects and relatively low efficacy, while catheter ablation, even if it is actually an established treatment, is an invasive procedure with intrinsic procedural risks and is frequently affected by patients' hemodynamic instability. Stereotactic arrhythmia radioablation for ventricular arrhythmias was developed as bail-out therapy in patients unresponsive to traditional treatments. Radiotherapy has been mainly applied in the oncological field, but new current perspectives have developed in the field of ventricular arrhythmias. Stereotactic arrhythmia radioablation provides an alternative non-invasive and painless therapeutic strategy for the treatment of previously detected cardiac arrhythmic substrate by three-dimensional intracardiac mapping or different tools. Since preliminary experiences have been reported, several retrospective studies, registries, and case reports have been published in the literature. Although, for now, stereotactic arrhythmia radioablation is considered an alternative palliative treatment for patients with refractory ventricular tachycardia and no other therapeutic options, this research field is currently extremely promising.
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Affiliation(s)
| | - Massimo Tritto
- Electrophysiology and Cardiac Pacing Unit, Humanitas Mater Domini Hospital, 21053 Castellanza, Italy
| | - Antonio Di Monaco
- Cardiology Department, General Regional Hospital F. Miulli, 70021 Acquaviva delle Fonti, Italy
| | - Marco Valerio Mariani
- Department of Cardiovascular, Respiratory, Nephrology, Anaesthesiology and Geriatric Sciences, Sapienza University of Rome, 00100 Rome, Italy
| | - Alessio Gasperetti
- Department of Cardiology, ASST-Fatebenefratelli Sacco, Luigi Sacco Hospital, University of Milan, 20157 Milan, Italy
| | - Paolo Compagnucci
- Cardiology and Arrhythmology Clinic, University Hospital Ospedali Riuniti Umberto I-Lancisi-Salesi, 60126 Ancona, Italy
| | - Daniele Muser
- Cardiothoracic Department, University Hospital, 33100 Udine, Italy
| | - Alberto Preda
- Department of Cardiac Electrophysiology and Arrhythmology, IRCCS San Raffaele Hospital, 20132 Milan, Italy
| | - Patrizio Mazzone
- Cardiothoracovascular Department, Electrophysiology Unit, Niguarda Hospital, 20162 Milan, Italy
| | - Sakis Themistoclakis
- Department of Cardiothoracic, Vascular Medicine and Intensive Care, Dell'Angelo Hospital, Mestre, 30174 Venice, Italy
| | - Corrado Carbucicchio
- Department of Clinical Electrophysiology and Cardiac Pacing, Centro Cardiologico Monzino IRCCS, 20138 Milan, Italy
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2
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Zhang DM, Navara R, Yin T, Szymanski J, Goldsztejn U, Kenkel C, Lang A, Mpoy C, Lipovsky CE, Qiao Y, Hicks S, Li G, Moore KMS, Bergom C, Rogers BE, Robinson CG, Cuculich PS, Schwarz JK, Rentschler SL. Cardiac radiotherapy induces electrical conduction reprogramming in the absence of transmural fibrosis. Nat Commun 2021; 12:5558. [PMID: 34561429 PMCID: PMC8463558 DOI: 10.1038/s41467-021-25730-0] [Citation(s) in RCA: 70] [Impact Index Per Article: 23.3] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/22/2020] [Accepted: 08/25/2021] [Indexed: 02/08/2023] Open
Abstract
Cardiac radiotherapy (RT) may be effective in treating heart failure (HF) patients with refractory ventricular tachycardia (VT). The previously proposed mechanism of radiation-induced fibrosis does not explain the rapidity and magnitude with which VT reduction occurs clinically. Here, we demonstrate in hearts from RT patients that radiation does not achieve transmural fibrosis within the timeframe of VT reduction. Electrophysiologic assessment of irradiated murine hearts reveals a persistent supraphysiologic electrical phenotype, mediated by increases in NaV1.5 and Cx43. By sequencing and transgenic approaches, we identify Notch signaling as a mechanistic contributor to NaV1.5 upregulation after RT. Clinically, RT was associated with increased NaV1.5 expression in 1 of 1 explanted heart. On electrocardiogram (ECG), post-RT QRS durations were shortened in 13 of 19 patients and lengthened in 5 patients. Collectively, this study provides evidence for radiation-induced reprogramming of cardiac conduction as a potential treatment strategy for arrhythmia management in VT patients.
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Affiliation(s)
- David M Zhang
- Center for Noninvasive Cardiac Radioablation, Washington University in St. Louis, School of Medicine, Saint Louis, MO, USA
- Department of Medicine, Cardiovascular Division, Washington University in St. Louis, School of Medicine, Saint Louis, MO, USA
| | - Rachita Navara
- Center for Noninvasive Cardiac Radioablation, Washington University in St. Louis, School of Medicine, Saint Louis, MO, USA
- Department of Medicine, Cardiovascular Division, Washington University in St. Louis, School of Medicine, Saint Louis, MO, USA
| | - Tiankai Yin
- Department of Medicine, Cardiovascular Division, Washington University in St. Louis, School of Medicine, Saint Louis, MO, USA
| | - Jeffrey Szymanski
- Department of Radiation Oncology, Washington University in St. Louis, School of Medicine, Saint Louis, MO, USA
| | - Uri Goldsztejn
- Department of Medicine, Cardiovascular Division, Washington University in St. Louis, School of Medicine, Saint Louis, MO, USA
- Department of Biomedical Engineering, Washington University in St. Louis, School of Medicine, Saint Louis, MO, USA
| | - Camryn Kenkel
- Department of Medicine, Cardiovascular Division, Washington University in St. Louis, School of Medicine, Saint Louis, MO, USA
- Department of Biomedical Engineering, Washington University in St. Louis, School of Medicine, Saint Louis, MO, USA
| | - Adam Lang
- Department of Pathology, Washington University in St. Louis, School of Medicine, Saint Louis, MO, USA
| | - Cedric Mpoy
- Department of Radiation Oncology, Washington University in St. Louis, School of Medicine, Saint Louis, MO, USA
| | - Catherine E Lipovsky
- Department of Medicine, Cardiovascular Division, Washington University in St. Louis, School of Medicine, Saint Louis, MO, USA
- Department of Developmental Biology, Washington University in St. Louis, School of Medicine, Saint Louis, MO, USA
| | - Yun Qiao
- Department of Medicine, Cardiovascular Division, Washington University in St. Louis, School of Medicine, Saint Louis, MO, USA
- Department of Biomedical Engineering, Washington University in St. Louis, School of Medicine, Saint Louis, MO, USA
| | - Stephanie Hicks
- Department of Medicine, Cardiovascular Division, Washington University in St. Louis, School of Medicine, Saint Louis, MO, USA
| | - Gang Li
- Department of Medicine, Cardiovascular Division, Washington University in St. Louis, School of Medicine, Saint Louis, MO, USA
- Department of Biomedical Engineering, Washington University in St. Louis, School of Medicine, Saint Louis, MO, USA
| | - Kaitlin M S Moore
- Center for Noninvasive Cardiac Radioablation, Washington University in St. Louis, School of Medicine, Saint Louis, MO, USA
- Department of Medicine, Cardiovascular Division, Washington University in St. Louis, School of Medicine, Saint Louis, MO, USA
| | - Carmen Bergom
- Center for Noninvasive Cardiac Radioablation, Washington University in St. Louis, School of Medicine, Saint Louis, MO, USA
- Department of Radiation Oncology, Washington University in St. Louis, School of Medicine, Saint Louis, MO, USA
| | - Buck E Rogers
- Department of Radiation Oncology, Washington University in St. Louis, School of Medicine, Saint Louis, MO, USA
| | - Clifford G Robinson
- Center for Noninvasive Cardiac Radioablation, Washington University in St. Louis, School of Medicine, Saint Louis, MO, USA
- Department of Medicine, Cardiovascular Division, Washington University in St. Louis, School of Medicine, Saint Louis, MO, USA
- Department of Radiation Oncology, Washington University in St. Louis, School of Medicine, Saint Louis, MO, USA
| | - Phillip S Cuculich
- Center for Noninvasive Cardiac Radioablation, Washington University in St. Louis, School of Medicine, Saint Louis, MO, USA
- Department of Medicine, Cardiovascular Division, Washington University in St. Louis, School of Medicine, Saint Louis, MO, USA
- Department of Radiation Oncology, Washington University in St. Louis, School of Medicine, Saint Louis, MO, USA
| | - Julie K Schwarz
- Center for Noninvasive Cardiac Radioablation, Washington University in St. Louis, School of Medicine, Saint Louis, MO, USA
- Department of Radiation Oncology, Washington University in St. Louis, School of Medicine, Saint Louis, MO, USA
| | - Stacey L Rentschler
- Center for Noninvasive Cardiac Radioablation, Washington University in St. Louis, School of Medicine, Saint Louis, MO, USA.
- Department of Medicine, Cardiovascular Division, Washington University in St. Louis, School of Medicine, Saint Louis, MO, USA.
- Department of Biomedical Engineering, Washington University in St. Louis, School of Medicine, Saint Louis, MO, USA.
- Department of Developmental Biology, Washington University in St. Louis, School of Medicine, Saint Louis, MO, USA.
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3
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Zhang DM, Szymanski J, Bergom C, Cuculich PS, Robinson CG, Schwarz JK, Rentschler SL. Leveraging Radiobiology for Arrhythmia Management: A New Treatment Paradigm? Clin Oncol (R Coll Radiol) 2021; 33:723-734. [PMID: 34535357 DOI: 10.1016/j.clon.2021.09.001] [Citation(s) in RCA: 5] [Impact Index Per Article: 1.7] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/27/2021] [Revised: 08/04/2021] [Accepted: 09/01/2021] [Indexed: 01/01/2023]
Abstract
Radiation therapy is a well-established approach for safely and non-invasively treating solid tumours and benign diseases with high precision and accuracy. Cardiac radiation therapy has recently emerged as a non-invasive treatment option for the management of refractory ventricular tachycardia. Here we summarise existing clinical and preclinical literature surrounding cardiac radiobiology and discuss how these studies may inform basic and translational research, as well as clinical treatment paradigms in the management of arrhythmias.
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Affiliation(s)
- D M Zhang
- Department of Medicine, Cardiovascular Division, Washington University in St. Louis, School of Medicine, Saint Louis, Missouri, USA
| | - J Szymanski
- Department of Radiation Oncology, Washington University in St. Louis, School of Medicine, Saint Louis, Missouri, USA
| | - C Bergom
- Department of Radiation Oncology, Washington University in St. Louis, School of Medicine, Saint Louis, Missouri, USA
| | - P S Cuculich
- Department of Medicine, Cardiovascular Division, Washington University in St. Louis, School of Medicine, Saint Louis, Missouri, USA; Department of Radiation Oncology, Washington University in St. Louis, School of Medicine, Saint Louis, Missouri, USA
| | - C G Robinson
- Department of Medicine, Cardiovascular Division, Washington University in St. Louis, School of Medicine, Saint Louis, Missouri, USA; Department of Radiation Oncology, Washington University in St. Louis, School of Medicine, Saint Louis, Missouri, USA
| | - J K Schwarz
- Department of Radiation Oncology, Washington University in St. Louis, School of Medicine, Saint Louis, Missouri, USA
| | - S L Rentschler
- Department of Medicine, Cardiovascular Division, Washington University in St. Louis, School of Medicine, Saint Louis, Missouri, USA; Department of Biomedical Engineering, Washington University in St. Louis, School of Medicine, Saint Louis, Missouri, USA; Department of Developmental Biology, Washington University in St. Louis, School of Medicine, Saint Louis, Missouri, USA.
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4
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Jarzebska N, Karetnikova ES, Markov AG, Kasper M, Rodionov RN, Spieth PM. Scarred Lung. An Update on Radiation-Induced Pulmonary Fibrosis. Front Med (Lausanne) 2021; 7:585756. [PMID: 33521012 PMCID: PMC7843914 DOI: 10.3389/fmed.2020.585756] [Citation(s) in RCA: 12] [Impact Index Per Article: 4.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/13/2020] [Accepted: 12/17/2020] [Indexed: 12/18/2022] Open
Abstract
Radiation-induced pulmonary fibrosis is a common severe long-time complication of radiation therapy for tumors of the thorax. Current therapeutic options used in the clinic include only supportive managements strategies, such as anti-inflammatory treatment using steroids, their efficacy, however, is far from being satisfactory. Recent studies have demonstrated that the development of lung fibrosis is a dynamic and complex process, involving the release of reactive oxygen species, activation of Toll-like receptors, recruitment of inflammatory cells, excessive production of nitric oxide and production of collagen by activated myofibroblasts. In this review we summarized the current state of knowledge on the pathophysiological processes leading to the development of lung fibrosis and we also discussed the possible treatment options.
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Affiliation(s)
- Natalia Jarzebska
- Department of Anesthesiology and Critical Care Medicine, University Hospital Dresden, Technische Universität Dresden, Dresden, Germany
- Division of Angiology, Department of Internal Medicine III, University Center for Vascular Medicine, University Hospital Dresden, Technische Universität Dresden, Dresden, Germany
| | | | - Alexander G. Markov
- Department of General Physiology, Saint-Petersburg State University, Saint Petersburg, Russia
| | - Michael Kasper
- Institute of Anatomy, Technische Universität Dresden, Dresden, Germany
| | - Roman N. Rodionov
- Division of Angiology, Department of Internal Medicine III, University Center for Vascular Medicine, University Hospital Dresden, Technische Universität Dresden, Dresden, Germany
| | - Peter M. Spieth
- Department of Anesthesiology and Critical Care Medicine, University Hospital Dresden, Technische Universität Dresden, Dresden, Germany
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5
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The role of connexin proteins and their channels in radiation-induced atherosclerosis. Cell Mol Life Sci 2021; 78:3087-3103. [PMID: 33388835 PMCID: PMC8038956 DOI: 10.1007/s00018-020-03716-3] [Citation(s) in RCA: 15] [Impact Index Per Article: 5.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/16/2020] [Revised: 10/29/2020] [Accepted: 11/17/2020] [Indexed: 02/08/2023]
Abstract
Radiotherapy is an effective treatment for breast cancer and other thoracic tumors. However, while high-energy radiotherapy treatment successfully kills cancer cells, radiation exposure of the heart and large arteries cannot always be avoided, resulting in secondary cardiovascular disease in cancer survivors. Radiation-induced changes in the cardiac vasculature may thereby lead to coronary artery atherosclerosis, which is a major cardiovascular complication nowadays in thoracic radiotherapy-treated patients. The underlying biological and molecular mechanisms of radiation-induced atherosclerosis are complex and still not fully understood, resulting in potentially improper radiation protection. Ionizing radiation (IR) exposure may damage the vascular endothelium by inducing DNA damage, oxidative stress, premature cellular senescence, cell death and inflammation, which act to promote the atherosclerotic process. Intercellular communication mediated by connexin (Cx)-based gap junctions and hemichannels may modulate IR-induced responses and thereby the atherosclerotic process. However, the role of endothelial Cxs and their channels in atherosclerotic development after IR exposure is still poorly defined. A better understanding of the underlying biological pathways involved in secondary cardiovascular toxicity after radiotherapy would facilitate the development of effective strategies that prevent or mitigate these adverse effects. Here, we review the possible roles of intercellular Cx driven signaling and communication in radiation-induced atherosclerosis.
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6
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The Role of Connexin 43 in Lung Disease. Life (Basel) 2020; 10:life10120363. [PMID: 33352732 PMCID: PMC7766413 DOI: 10.3390/life10120363] [Citation(s) in RCA: 4] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Key Words] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/13/2020] [Revised: 12/15/2020] [Accepted: 12/17/2020] [Indexed: 01/10/2023] Open
Abstract
The term lung disease describes a broad category of disorders that impair lung function. More than 35 million Americans have a preventable chronic lung disease with high mortality rates due to limited treatment efficacy. The recent increase in patients with lung disease highlights the need to increase our understanding of mechanisms driving lung inflammation. Connexins, gap junction proteins, and more specifically connexin 43 (Cx43), are abundantly expressed in the lung and are known to play a role in lung diseases. This review focuses on the role of Cx43 in pathology associated with acute respiratory distress syndrome (ARDS), chronic obstructive pulmonary disease (COPD) and asthma. Additionally, we discuss the role of Cx43 in preventing disease through the transfer of mitochondria between cells. We aim to highlight the need to better understand what cell types are expressing Cx43 and how this expression influences lung disease.
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Norepinephrine Leads to More Cardiopulmonary Toxicities than Epinephrine by Catecholamine Overdose in Rats. TOXICS 2020; 8:toxics8030069. [PMID: 32947820 PMCID: PMC7560392 DOI: 10.3390/toxics8030069] [Citation(s) in RCA: 4] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Subscribe] [Scholar Register] [Received: 08/13/2020] [Revised: 09/11/2020] [Accepted: 09/13/2020] [Indexed: 12/15/2022]
Abstract
While catecholamines like epinephrine (E) and norepinephrine (NE) are commonly used in emergency medicine, limited studies have discussed the harm of exogenously induced catecholamine overdose. We investigated the possible toxic effects of excessive catecholamine administration on cardiopulmonary function and structure via continuous 6 h intravenous injection of E and/or NE in rats. Heart rate, echocardiography, and ventricular pressure were measured throughout administration. Cardiopulmonary structure was also assessed by examining heart and lung tissue. Consecutive catecholamine injections induced severe tachycardia. Echocardiography results showed NE caused worse dysfunction than E. Simultaneously, both E and NE led to higher expression of Troponin T and connexin43 in the whole ventricles, which increased further with E+NE administration. The NE and E+NE groups showed severe pulmonary edema while all catecholamine-administering groups demonstrated reduced expression of receptor for advanced glycation end products and increased connexin43 levels in lung tissue. The right ventricle was more vulnerable to catecholamine overdose than the left. Rats injected with NE had a lower survival rate than those injected with E within 6 h. Catecholamine overdose induces acute lung injuries and ventricular cardiomyopathy, and E+NE is associated with a more severe outcome. The similarities of the results between the NE and E+NE groups may indicate a predominant role of NE in determining the overall cardiopulmonary damage. The results provide important clinical insights into the pathogenesis of catecholamine storm.
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Amino M, Yoshioka K, Kamada T, Furusawa Y. The Potential Application of Heavy Ion Beams in the Treatment of Arrhythmia: The Role of Radiation-Induced Modulation of Connexin43 and the Sympathetic Nervous System. Int J Part Ther 2018; 5:140-150. [PMID: 31773026 DOI: 10.14338/ijpt-18-00022.1] [Citation(s) in RCA: 4] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/12/2018] [Accepted: 06/12/2018] [Indexed: 11/21/2022] Open
Abstract
It has been known that heart disease-such as myocardial infarction (MI), cardiac hypertrophy, or heart failure-alters the molecular structure and function of the gap junction, which can lead to an abnormal heart rhythm. Radiation has been shown to modulate intercellular communication in the skin and lungs by increasing connexin43 (Cx43) expression. Understanding how Cx43 upregulation is induced in a diseased heart can help provide a new perspective to radiation therapy for arrhythmias. In a recent study with rabbits after MI, carbon ions were accelerated to 290 MeV/u and extracted in the air; a biologically (cell kill) uniform 6-cm spread-out Bragg peak beam was generated, and beam tissue depth was set to 30 mm with energy degraders to the depth position. Targeted heavy ion irradiation (THIR) with 15 Gy to the left ventricle increased Cx43 expression, improved conductivity, decreased the spatial heterogeneity of repolarization, and reduced the vulnerability of rabbit hearts to ventricular arrhythmias after MI. In clinically normal rabbits, THIR > = 10 Gy caused a significant dose-dependent increase of Cx43 protein and messenger RNA 2 weeks after irradiation. The left (irradiated) and right (nonirradiated) ventricles exhibited circumferential upregulation of Cx43 lasting for at least 1 year. There were no significant changes in electrocardiograms and echocardiograms, indicating no apparent injury for 1 year. A single exposure of 135 MeV/u THIR with 15 Gy to a dog heart attenuated vulnerability to ventricular arrhythmia after the induction of MI for at least 1 year through the modulation of Cx43 expression. This long-lasting remodeling effect on gap junctions may lay the groundwork to novel therapies against life-threatening ventricular arrhythmias in structural heart disease. To date, there have been few investigations into the effects of carbon-ion irradiation on electrophysiological properties in the human heart. Patients with mediastinum cancer were investigated for 5 years after treatment that included irradiation to the heart, and investigators found that carbon-ion beam irradiation to the heart is not immediately cardiotoxic and demonstrates consistent signals of arrhythmia reduction. Its practical application in non-cancer treatment, such as in arrhythmia treatment, is highly anticipated.
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Affiliation(s)
- Mari Amino
- Department of Cardiovascular Medicine, Tokai University, Isehara, Japan
| | - Koichiro Yoshioka
- Department of Cardiovascular Medicine, Tokai University, Isehara, Japan
| | - Tadashi Kamada
- Department of Cardiovascular Medicine, Tokai University, Isehara, Japan
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The pivotal role of extracellular signal-regulated kinase in gap junction-mediated regulation of TXNIP. Cell Signal 2017; 38:116-126. [PMID: 28694028 DOI: 10.1016/j.cellsig.2017.07.001] [Citation(s) in RCA: 6] [Impact Index Per Article: 0.9] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/15/2017] [Revised: 07/06/2017] [Accepted: 07/06/2017] [Indexed: 12/27/2022]
Abstract
Gap junctions (GJs) play a major role in the control of cell structure, function, and metabolism. However, the molecular mechanisms involved are still poorly understood. Given that thioredoxin-interacting protein (TXNIP) regulates a broad range of cellular processes, we tested the possible involvement of TXNIP. Disruption of GJs with several chemical GJ inhibitors or connexin43 (Cx43) siRNA potently suppressed TXNIP, which was preceded by an activation of extracellular signal-regulated kinase (ERK). Inhibition of ERK or its upstream kinase with chemical inhibitors prevented the reduction of TXNIP. On the contrary, activation of ERK with mitogens or phosphatase inhibitors reproduced the suppressive effects of GJs. Further analysis revealed that dysfunction of GJs promoted TXNIP phosphorylation, ubiquitination, and degradation, whereas inhibition of ERK exerted the opposite effects. Moreover, inhibition of GJs elevated Glut1 and enhanced cell resistance to ER stress in a similar way to TXNIP downregulation. Collectively, our study thus characterizes ERK-mediated suppression of TXNIP as a presently unreported mechanism by which GJs regulate cell behaviors.
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Decrock E, Hoorelbeke D, Ramadan R, Delvaeye T, De Bock M, Wang N, Krysko DV, Baatout S, Bultynck G, Aerts A, Vinken M, Leybaert L. Calcium, oxidative stress and connexin channels, a harmonious orchestra directing the response to radiotherapy treatment? BIOCHIMICA ET BIOPHYSICA ACTA-MOLECULAR CELL RESEARCH 2017; 1864:1099-1120. [DOI: 10.1016/j.bbamcr.2017.02.007] [Citation(s) in RCA: 31] [Impact Index Per Article: 4.4] [Reference Citation Analysis] [Track Full Text] [Subscribe] [Scholar Register] [Received: 11/30/2016] [Revised: 02/02/2017] [Accepted: 02/04/2017] [Indexed: 02/07/2023]
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Amino M, Yoshioka K, Furusawa Y, Tanaka S, Kawabe N, Hashida T, Tsukada T, Izumi M, Inokuchi S, Tanabe T, Ikari Y. Inducibility of Ventricular Arrhythmia 1 Year Following Treatment with Heavy Ion Irradiation in Dogs with Myocardial Infarction. PACING AND CLINICAL ELECTROPHYSIOLOGY: PACE 2017; 40:379-390. [PMID: 28158934 DOI: 10.1111/pace.13031] [Citation(s) in RCA: 21] [Impact Index Per Article: 3.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Subscribe] [Scholar Register] [Received: 10/30/2016] [Revised: 01/06/2017] [Accepted: 01/23/2017] [Indexed: 11/28/2022]
Abstract
BACKGROUND Targeted external heavy ion irradiation (THIR) of rabbit hearts 2 weeks after myocardial infarction (MI) reduced the vulnerability of fatal ventricular tachyarrhythmias (VT/VF) in association with the increased connexin43 (Cx43). Increased Cx43 was maintained for at least 1 year in normal rabbits, but the long-term antiarrhythmic effects in the MI model are unknown. We investigated the propensity for late potentials and VT/VF inducibility. METHODS Intracoronary injection of microspheres was performed to induce nontransmural MI in anesthetized eight beagles. Four beagles were treated with THIR (12 C6+ , 15 Gy) 2 weeks later (MI + THIR group), and four without THIR served as controls (MI group). Signal-averaged electrocardiography, programmed electrical stimulation, immunohistochemical analysis, and echocardiograms were performed at 1 year. RESULTS Filtered QRS duration was exacerbated after MI and remained unchanged for 1 year in the MI group (118 ± 1.4 ms), but significantly returned toward baseline in the MI + THIR group (109 ± 6.9 ms). Similarly, root mean square voltage of the last 40 ms was exacerbated after MI, but recovered after THIR. VT/VF inducibility decreased to 25% in the MI + THIR group compared with 100% in the MI group. Immunostaining Cx43 expression in cardiac tissues significantly increased by 24-45% in the MI + THIR group. Left ventricular ejection fractions remained within the normal range in both groups. CONCLUSION A single exposure of the dog heart to 12 C irradiation attenuated vulnerability to ventricular arrhythmia after the induction of MI for at least 1 year through the modulation of Cx43 expression.
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Affiliation(s)
- Mari Amino
- Department of Cardiovascular Medicine, Tokai University, Isehara, Japan
| | - Koichiro Yoshioka
- Department of Cardiovascular Medicine, Tokai University, Isehara, Japan
| | | | - Sachie Tanaka
- Support Center for Medical Research and Education, Tokai University, Shimokasuya, Japan
| | - Noboru Kawabe
- Support Center for Medical Research and Education, Tokai University, Shimokasuya, Japan
| | - Tadashi Hashida
- Department of Cardiovascular Medicine, Tokai University, Isehara, Japan
| | | | | | - Sadaki Inokuchi
- Department of Critical Care and Medicine, Tokai University, Isehara, Japan
| | - Teruhisa Tanabe
- Department of Cardiovascular Medicine, Tokai University, Isehara, Japan
| | - Yuji Ikari
- Department of Cardiovascular Medicine, Tokai University, Isehara, Japan
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12
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Wong P, Laxton V, Srivastava S, Chan YWF, Tse G. The role of gap junctions in inflammatory and neoplastic disorders (Review). Int J Mol Med 2017; 39:498-506. [PMID: 28098880 PMCID: PMC5360388 DOI: 10.3892/ijmm.2017.2859] [Citation(s) in RCA: 29] [Impact Index Per Article: 4.1] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/09/2016] [Accepted: 12/23/2016] [Indexed: 12/29/2022] Open
Abstract
Gap junctions are intercellular channels made of connexin proteins, mediating both electrical and biochemical signals between cells. The ability of gap junction proteins to regulate immune responses, cell proliferation, migration, apoptosis and carcinogenesis makes them attractive therapeutic targets for treating inflammatory and neoplastic disorders in different organ systems. Alterations in gap junction profile and expression levels are observed in hyperproliferative skin disorders, lymphatic vessel diseases, inflammatory lung diseases, liver injury and neoplastic disorders. It is now recognized that the therapeutic effects mediated by traditional pharmacological agents are dependent upon gap junction communication and may even act by influencing gap junction expression or function. Novel strategies for modulating the function or expression of connexins, such as the use of synthetic mimetic peptides and siRNA technology are considered.
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Affiliation(s)
- Pui Wong
- School of Biomedical Sciences, Li Ka Shing Faculty of Medicine, University of Hong Kong, Hong Kong, SAR, P.R. China
| | - Victoria Laxton
- Intensive Care Department, Royal Brompton and Harefield NHS Foundation Trust, London SW3 6NP
| | | | - Yin Wah Fiona Chan
- School of Biological Sciences, University of Cambridge, Cambridge CB2 1AG, UK
| | - Gary Tse
- Department of Medicine and Therapeutics
- Li Ka Shing Institute of Health Sciences, Faculty of Medicine, Chinese University of Hong Kong, Hong Kong, SAR, P.R. China
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13
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Expression and role of connexin-based gap junctions in pulmonary inflammatory diseases. Pharmacol Ther 2016; 164:105-19. [PMID: 27126473 DOI: 10.1016/j.pharmthera.2016.04.004] [Citation(s) in RCA: 22] [Impact Index Per Article: 2.8] [Reference Citation Analysis] [Abstract] [Key Words] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/18/2015] [Accepted: 04/07/2016] [Indexed: 01/03/2023]
Abstract
Connexins are transmembrane proteins that can generate intercellular communication channels known as gap junctions. They contribute to the direct movement of ions and larger cytoplasmic solutes between various cell types. In the lung, connexins participate in a variety of physiological functions, such as tissue homeostasis and host defence. In addition, emerging evidence supports a role for connexins in various pulmonary inflammatory diseases, such as asthma, pulmonary hypertension, acute lung injury, lung fibrosis or cystic fibrosis. In these diseases, the altered expression of connexins leads to disruption of normal intercellular communication pathways, thus contributing to various pathophysiological aspects, such as inflammation or tissue altered reactivity and remodeling. The present review describes connexin structure and organization in gap junctions. It focuses on connexins in the lung, including pulmonary bronchial and arterial beds, by looking at their expression, regulation and physiological functions. This work also addresses the issue of connexin expression alteration in various pulmonary inflammatory diseases and describes how targeting connexin-based gap junctions with pharmacological tools, synthetic blocking peptides or genetic approaches, may open new therapeutic perspectives in the treatment of these diseases.
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Abstract
The different types of cells in the lung, from the conducting airway epithelium to the alveolar epithelium and the pulmonary vasculature, are interconnected by gap junctions. The specific profile of gap junction proteins, the connexins, expressed in these different cell types forms compartments of intercellular communication that can be further shaped by the release of extracellular nucleotides via pannexin1 channels. In this review, we focus on the physiology of connexins and pannexins and describe how this lung communication network modulates lung function and host defenses in conductive and respiratory airways.
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Affiliation(s)
- Davide Losa
- Geneva University Hospitals and University of Geneva, 1211 Geneva, Switzerland
- The ithree Institute, University of Technology Sydney, 2007 Ultimo, NSW Australia
| | - Marc Chanson
- Geneva University Hospitals and University of Geneva, 1211 Geneva, Switzerland
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Effect of P2X7 receptor knockout on AQP-5 expression of type I alveolar epithelial cells. PLoS One 2014; 9:e100282. [PMID: 24941004 PMCID: PMC4062497 DOI: 10.1371/journal.pone.0100282] [Citation(s) in RCA: 16] [Impact Index Per Article: 1.6] [Reference Citation Analysis] [Abstract] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/13/2013] [Accepted: 05/26/2014] [Indexed: 01/13/2023] Open
Abstract
P2X7 receptors, ATP-gated cation channels, are specifically expressed in alveolar epithelial cells. The pathophysiological function of this lung cell type, except a recently reported putative involvement in surfactant secretion, is unknown. In addition, P2X7 receptor-deficient mice show reduced inflammation and lung fibrosis after exposure with bleomycin. To elucidate the role of the P2X7 receptor in alveolar epithelial type I cells we characterized the pulmonary phenotype of P2X7 receptor knockout mice by using immunohistochemistry, western blot analysis and real-time RT PCR. No pathomorphological signs of fibrosis were found. Results revealed, however, a remarkable loss of aquaporin-5 protein and mRNA in young knockout animals. Additional in vitro experiments with bleomycin treated precision cut lung slices showed a greater sensitivity of the P2X7 receptor knockout mice in terms of aquaporin-5 reduction as wild type animals. Finally, P2X7 receptor function was examined by using the alveolar epithelial cell lines E10 and MLE-12 for stimulation experiments with bleomycin. The in vitro activation of P2X7 receptor was connected with an increase of aquaporin-5, whereas the inhibition of the receptor with oxidized ATP resulted in down regulation of aquaporin-5. The early loss of aquaporin-5 which can be found in different pulmonary fibrosis models does not implicate a specific pathogenetic role during fibrogenesis.
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Johansson HM, Newman DR, Sannes PL. Whole-genome analysis of temporal gene expression during early transdifferentiation of human lung alveolar epithelial type 2 cells in vitro. PLoS One 2014; 9:e93413. [PMID: 24690998 PMCID: PMC3972118 DOI: 10.1371/journal.pone.0093413] [Citation(s) in RCA: 8] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/20/2013] [Accepted: 03/05/2014] [Indexed: 12/21/2022] Open
Abstract
It is generally accepted that the surfactant-producing pulmonary alveolar epithelial type II (AT2) cell acts as the progenitor of the type I (AT1) cell, but the regulatory mechanisms involved in this relationship remain the subject of active investigation. While previous studies have established a number of specific markers that are expressed during transdifferentiation from AT2 to AT1 cells, we hypothesized that additional, previously unrecognized, signaling pathways and relevant cellular functions are transcriptionally regulated at early stages of AT2 transition. In this study, a discovery-based gene expression profile analysis was undertaken of freshly isolated human AT2 (hAT2) cells grown on extracellular matrix (ECM) substrata known to either support (type I collagen) or retard (Matrigel) the early transdifferentiation process into hAT1-like cells over the first three days. Cell type-specific expression patterns analyzed by Illumina Human HT-12 BeadChip yielded over 300 genes that were up- or down-regulated. Candidate genes significantly induced or down-regulated during hAT2 transition to hAT1-like cells compared to non-transitioning hAT2 cells were identified. Major functional groups were also recognized, including those of signaling and cytoskeletal proteins as well as genes of unknown function. Expression of established signatures of hAT2 and hAT1 cells, such as surfactant proteins, caveolin-1, and channels and transporters, was confirmed. Selected novel genes further validated by qRT-PCR, protein expression analysis, and/or cellular localization included SPOCK2, PLEKHO1, SPRED1, RAB11FIP1, PTRF/CAVIN-1 and RAP1GAP. These results further demonstrate the utility of genome-wide analysis to identify relevant, novel cell type-specific signatures of early ECM-regulated alveolar epithelial transdifferentiation processes in vitro.
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Affiliation(s)
- Helena Morales Johansson
- Department of Molecular Biomedical Sciences, Center for Comparative Medicine and Translational Research, College of Veterinary Medicine, North Carolina State University, Raleigh, North Carolina, United States of America
| | - Donna R. Newman
- Department of Molecular Biomedical Sciences, Center for Comparative Medicine and Translational Research, College of Veterinary Medicine, North Carolina State University, Raleigh, North Carolina, United States of America
| | - Philip L. Sannes
- Department of Molecular Biomedical Sciences, Center for Comparative Medicine and Translational Research, College of Veterinary Medicine, North Carolina State University, Raleigh, North Carolina, United States of America
- * E-mail:
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Koval M, Billaud M, Straub AC, Johnstone SR, Zarbock A, Duling BR, Isakson BE. Spontaneous lung dysfunction and fibrosis in mice lacking connexin 40 and endothelial cell connexin 43. THE AMERICAN JOURNAL OF PATHOLOGY 2011; 178:2536-46. [PMID: 21641379 PMCID: PMC3124229 DOI: 10.1016/j.ajpath.2011.02.045] [Citation(s) in RCA: 39] [Impact Index Per Article: 3.0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Received: 07/24/2010] [Revised: 12/30/2010] [Accepted: 02/01/2011] [Indexed: 12/31/2022]
Abstract
Gap junction proteins (connexins) facilitate intercellular communication and serve several roles in regulation of tissue function and remodeling. To examine the physiologic effects of depleting two prominent endothelial connexins, Cx40 and Cx43, transgenic mice were generated by breeding Cx40-deficient mice (Cx40(-/-)) with a vascular endothelial cell (VEC)-specific Cx43-deficient mouse strain (VEC Cx43(-/-)) to produce double-connexin knockout mice (VEC Cx43(-/-)/Cx40(-/-)). The life span in VEC Cx43(-/-)/Cx40(-/-) mice was dramatically shortened, which correlated with severe spontaneous lung abnormalities as the mice aged including increased fibrosis, aberrant alveolar remodeling, and increased lung fibroblast content. Moreover, VEC Cx43(-/-)/Cx40(-/-) mice exhibited cardiac hypertrophy and hypertension. Because VEC Cx43(-/-)/Cx40(-/-) mice demonstrated phenotypic hallmarks that were remarkably similar to those in mice deficient in caveolin-1, pulmonary caveolin expression was examined. Lungs from VEC Cx43(-/-)/Cx40(-/-) mice demonstrated significantly decreased expression of caveolin-1 and caveolin-2. This suggests that expression of caveolin-1 may be linked to expression of Cx40 and endothelial Cx43. Moreover, the phenotype of caveolin-1(-/-) mice and VEC Cx43(-/-)/Cx40(-/-) mice may arise via a common mechanism.
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Affiliation(s)
- Michael Koval
- Division of Pulmonary, Allergy, and Critical Care Medicine, Department of Medicine, Emory University School of Medicine, Atlanta, Georgia
- Department of Cell Biology, Emory University School of Medicine, Atlanta, Georgia
| | - Marie Billaud
- Robert M. Berne Cardiovascular Research Center, University of Virginia School of Medicine, Charlottesville, Virginia
| | - Adam C. Straub
- Robert M. Berne Cardiovascular Research Center, University of Virginia School of Medicine, Charlottesville, Virginia
| | - Scott R. Johnstone
- Robert M. Berne Cardiovascular Research Center, University of Virginia School of Medicine, Charlottesville, Virginia
| | - Alexander Zarbock
- Department of Anesthesiology and Critical Care Medicine, University of Münster, Münster, Germany
- Max-Planck-Institute of Molecular Biomedicine, Münster, Germany
| | - Brian R. Duling
- Robert M. Berne Cardiovascular Research Center, University of Virginia School of Medicine, Charlottesville, Virginia
- Department of Molecular Physiology and Biological Physics, University of Virginia School of Medicine, Charlottesville, Virginia
| | - Brant E. Isakson
- Robert M. Berne Cardiovascular Research Center, University of Virginia School of Medicine, Charlottesville, Virginia
- Department of Molecular Physiology and Biological Physics, University of Virginia School of Medicine, Charlottesville, Virginia
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Role of connexin43 and ATP in long-range bystander radiation damage and oncogenesis in vivo. Oncogene 2011; 30:4601-8. [PMID: 21602884 DOI: 10.1038/onc.2011.176] [Citation(s) in RCA: 60] [Impact Index Per Article: 4.6] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/17/2023]
Abstract
Ionizing radiation is a genotoxic agent and human carcinogen. Recent work has questioned long-held dogmas by showing that cancer-associated genetic alterations occur in cells and tissues not directly exposed to radiation, questioning the robustness of the current system of radiation risk assessment. In vitro, diverse mechanisms involving secreted soluble factors, gap junction intercellular communication (GJIC) and oxidative metabolism are proposed to mediate these indirect effects. In vivo, the mechanisms behind long-range 'bystander' responses remain largely unknown. Here, we investigate the role of GJIC in propagating radiation stress signals in vivo, and in mediating radiation-associated bystander tumorigenesis in mouse central nervous system using a mouse model in which intercellular communication is downregulated by targeted deletion of the connexin43 (Cx43) gene. We show that GJIC is critical for transmission of oncogenic radiation damage to the non-targeted cerebellum, and that a mechanism involving adenosine triphosphate release and upregulation of Cx43, the major GJIC constituent, regulates transduction of oncogenic damage to unirradiated tissues in vivo. Our data provide a novel hypothesis for transduction of distant bystander effects and suggest that the highly branched nervous system, similar to the vascular network, has an important role.
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Losa D, Chanson M, Crespin S. Connexins as therapeutic targets in lung disease. Expert Opin Ther Targets 2011; 15:989-1002. [PMID: 21585238 DOI: 10.1517/14728222.2011.584875] [Citation(s) in RCA: 32] [Impact Index Per Article: 2.5] [Reference Citation Analysis] [Abstract] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/05/2022]
Abstract
INTRODUCTION The lung is a mechanically active system exposed to the external environment and is particularly sensitive to injury and inflammation. Studies have identified intercellular communication pathways that promote proper lung function in response to injury and disease. These pathways involve connexins (Cxs) and gap junctional intercellular communication (GJIC). AREAS COVERED IN THIS REVIEW The functional expression of Cxs in airway epithelium and vasculature, under normal and pathological conditions, is reviewed. Inhibition of GJIC and/or silencing of Cxs have been shown to modulate the course of disease development. Cx-based channels: i) coordinate ciliary beating and fluid transport to promote clearance of particulates, ii) regulate secretion of pulmonary surfactant, in response to deep inhalation by interconnecting type I and type II alveolar epithelial cells, and iii) are key mediators of pro- and anti-inflammatory signalling by the pulmonary endothelium, in order to modulate leukocyte recruitment from the circulation. EXPERT OPINION Cx-based channels play several central roles in promoting a regulated inflammatory response and facilitating lung repair, thus enabling the pulmonary epithelium and vasculature to behave as integrated systems. Several pathologies can disrupt the normal communication pathways required for proper lung function, including acute lung injury, asthma, cystic fibrosis, pulmonary fibrosis and cancer.
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Affiliation(s)
- Davide Losa
- Geneva University Hospitals and University of Geneva, Foundation for Medical Research , Laboratory of Clinical Investigation III, Switzerland
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20
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Banaz-Yaşar F, Tischka R, Iliakis G, Winterhager E, Gellhaus A. Cell Line Specific Modulation of Connexin43 Expression after Exposure to Ionizing Radiation. ACTA ACUST UNITED AC 2009; 12:249-59. [PMID: 16531320 DOI: 10.1080/15419060500514101] [Citation(s) in RCA: 12] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 02/05/2023]
Abstract
Gap junctional intercellular communication plays a significant role in mediating radiation-induced bystander effects. However, the level of Cx43 itself is influenced by ionizing radiation, which could modify the bystander effect. Here we have investigated several cell lines for the modulation of Cx43 expression 24 h after irradiation with 5 Gy X-rays. The mouse endothelial cell line bEnd3 revealed a significantly elevated level of Cx43 already 15 min after exposure to X-rays, whereas human hybrid endothelial cells (EA.hy926) exhibited a transient downregulation of Cx43 mRNA. No obvious changes in the communication properties of the different cell lines could be observed after irradiation. The communication-deficient malignant human trophoblast cell line Jeg3 stably transfected with Cx43 did not reveal any induction of endogenous nor alteration in the exogenous Cx43 transcript level upon exposure to 5 Gy. Taken together, our data show a cell line specific modulation of Cx43 expression after exposure to X-rays.
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Johnson LN, Koval M. Cross-talk between pulmonary injury, oxidant stress, and gap junctional communication. Antioxid Redox Signal 2009; 11:355-67. [PMID: 18816185 PMCID: PMC2933150 DOI: 10.1089/ars.2008.2183] [Citation(s) in RCA: 66] [Impact Index Per Article: 4.4] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 01/11/2023]
Abstract
Gap junction channels interconnect several different types of cells in the lung, ranging from the alveolar epithelium to the pulmonary vasculature, each of which expresses a unique subset of gap junction proteins (connexins). Major lung functions regulated by gap junctional communication include coordination of ciliary beat frequency and inflammation. Gap junctions help enable the alveolus to regulate surfactant secretion as an integrated system, in which type I cells act as mechanical sensors that transmit calcium transients to type II cells. Thus, disruption of epithelial gap junctional communication, particularly during acute lung injury, can interfere with these processes and increase the severity of injury. Consistent with this, connexin expression is altered during lung injury, and connexin-deficiency has a negative impact on the injury response and lung-growth control. It has recently been shown that alcohol abuse is a significant risk factor associated with acute respiratory distress syndrome. Oxidant stress and hormone-signaling cascades in the lung induced by prolonged alcohol ingestion are discussed, as well as the effects of these pathways on connexin expression and function.
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Affiliation(s)
- Latoya N Johnson
- Division of Pulmonary, Allergy and Critical Care Medicine, and Emory Alcohol and Lung Biology Center, Emory University School of Medicine, Atlanta, Georgia 30322, USA
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22
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Volonté C, D'Ambrosi N. Membrane compartments and purinergic signalling: the purinome, a complex interplay among ligands, degrading enzymes, receptors and transporters. FEBS J 2008; 276:318-29. [PMID: 19076212 DOI: 10.1111/j.1742-4658.2008.06793.x] [Citation(s) in RCA: 88] [Impact Index Per Article: 5.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/20/2022]
Abstract
Receptors should be properly analysed in view of the microenvironment in which they are embedded. Therefore, the concept of 'receptosome' was formulated to the complex interactions taking place between receptors and other proteins at the plasma membrane level, and to explain very heterogeneous or divergent cellular responses to common epigenetic factors and modifications to the extracellular environment. The receptosome thus becomes a molecular network connecting transmitters, hormones or growth factors, to both their specific receptors and unique downstream effector proteins. As an example of receptosome, we introduce here the 'purinome' as molecular complex responsible for the biological effects of extracellular purine and pyrimidine ligands. In addition to a vast heterogeneity of purinergic ligands, the purinome thus consists of ectonucleotide-metabolizing enzymes hydrolysing nucleoside phosphates, purinergic receptors classified as P1 for adenosine/AMP and P2 for nucleosides tri-/diphosphates, nucleoside transporters with both equilibrative and concentrative properties and finally, nucleotide channels and transporters. Notably, these purinergic elements are not independent, but they play tightly concerted actions under physiological conditions. As a whole and not singularly, they trigger, maintain and terminate the purinergic signalling. This signifies that the purinome is not a new, mere definition of juxtaposed purinergic units, but rather the experimental evidence of complex and dynamic molecular cross-talk and cooperation networks. Alteration of this dynamic equilibrium may even participate in many pathological states. As a consequence, to be successful against pathological conditions, the genetic/pharmacological manipulation of purinergic mechanisms must go well beyond single proteins, and be more holistically oriented.
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Abstract
Preconditioning is an endogenous mechanism in which a nonlethal exposure increases cellular resistance to subsequent additional severe injury. Here we show that connexin 43 (Cx43) plays a key role in protection afforded by preconditioning. Cx43 null mice were insensitive to hypoxic preconditioning, whereas wild-type littermate mice exhibited a significant reduction in infarct volume after occlusion of the middle cerebral artery. In cultures, Cx43-deficient cells responded to preconditioning only after exogenous expression of Cx43, and protection was attenuated by small interference RNA or by channel blockers. Our observations indicate that preconditioning reduced degradation of Cx43, resulting in a marked increase in the number of plasma membrane Cx43 hemichannels. Consequently, efflux of ATP through hemichannels led to accumulation of its catabolic product adenosine, a potent neuroprotective agent. Thus, adaptive modulation of Cx43 can offset environmental stress by adenosine-mediated elevation of cellular resistance.
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Avanzo JL, Mennecier G, Mesnil M, Hernandez-Blazquez FJ, Fukumasu H, da Silva TC, Rao KVK, Dagli MLZ. Deletion of a single allele of Cx43 is associated with a reduction in the gap junctional intercellular communication and increased cell proliferation of mouse lung pneumocytes type II. Cell Prolif 2007; 40:411-21. [PMID: 17531084 PMCID: PMC6496494 DOI: 10.1111/j.1365-2184.2007.00440.x] [Citation(s) in RCA: 15] [Impact Index Per Article: 0.9] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 10/23/2022] Open
Abstract
OBJECTIVES Connexins (Cx) are proteins that form the gap junctional channels at neighbouring plasma membranes between adjacent cells. Cxs are involved in cell communication, which is reportedly correlated with cell proliferation and differentiation. Alterations in connexin expression and/or gap junctional intercellular communication (GJIC) capacity have long been postulated to be important in a number of pathological conditions including cancer. This study was performed to determine the consequences of the deletion of a single allele of Gja1 (Cx43 gene) in Alveolar Type II cells (APTIIs), and its impact on GJIC and cell proliferation. MATERIAL AND METHODS In order to do so, APTIIs from wild type (Cx43(+/+)) and heterozygous (Cx43(+/-)) mice were harvested and cultured for 4 days. The GJIC capacity was evaluated by scrape-loading method, with the transfer of lucifer yellow dye. The expression of Cx43 was evaluated by immunofluorescence method and Western blotting. Cell proliferation was evaluated by 3-(4,5-dimethylthazol-2-yl)-2,5-diphenyltetrazolium bromide assay. RESULTS It was observed that GJIC capacity was significantly reduced and cell proliferation index was significantly higher in Cx43(+/-) cells compared to Cx43(+/+) cells. CONCLUSIONS These results show that knocking out one allele of Cx43 leads to a lower cell to cell communication capacity, and consequently induces a higher cell proliferation. Because chemically induced lung adenomas in mice are known to originate from APTIIs, these alterations may play a critical role in their susceptibility to lung carcinogenesis.
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Affiliation(s)
- J L Avanzo
- Laboratory of Experimental Oncology, Department of Pathology, Faculty of Veterinary Medicine and Animal Science, University of São Paulo, Brazil
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Huang X, Huang G, Zheng C. Expression of connexin43 in rat epithelial cells and fibroblasts. Curr Med Sci 2005; 25:206-8. [PMID: 16116974 DOI: 10.1007/bf02873578] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/22/2004] [Indexed: 05/04/2023]
Abstract
To explore the role of connexin43 (Cx43) in gap junctional intercellular communication (GJIC) and propagated sensation along meridians, the expression of Cx43 in the rat epithelial cells and fibroblasts was studied both in vitro and in vivo. With the in vitro study, the rat epithelial cells and fibroblasts were cultured together, and the localization of Cx43 was detected by immunohistochemistry and indirect immunofluorescent cytochemistry and under confocal microscopy. And the expression of Cx43 on the surface of the cells was examined by flow cytometry. With the in vivo examination, 20 SD rats were randomized into control group (n = 10) and electrical acupuncture group (EA group, n = 10). EA ( 0.5-1. 5 V, 4-16 Hz , 30 min) was applied to "Zusanli" acupoint for 30 min at rat's hind paw, the localization of Cx43 was immunohistochemically detected. The immunohistochemical staining and indirect immunfluorescent cytochemistry showed that Cx43 was localized on the surface of the cells and in the cytoplasm. The relative expression level of Cx43 on the cellular membrane surfaces of the rat epithelial cells and fibroblasts, as determined by FACS, were 13.91% and 29.53% respectively. Our studied suggested that Cx43 might be involved in GJIC and propagated sensation along meridians.
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Affiliation(s)
- Xiaotao Huang
- Institute of Integrated Traditional Chinese & Western Medicine, Tongji Hospital, Tongji Medical College, Huazhong University of Science and Technology, Wuhan 430030, China
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Barth K, Gentsch M, Bläsche R, Pfüller A, Parshyna I, Koslowski R, Barth G, Kasper M. Distribution of caveolin-1 and connexin43 in normal and injured alveolar epithelial R3/1 cells. Histochem Cell Biol 2004; 123:239-47. [PMID: 15856276 DOI: 10.1007/s00418-004-0727-4] [Citation(s) in RCA: 18] [Impact Index Per Article: 0.9] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Accepted: 10/27/2004] [Indexed: 11/29/2022]
Abstract
Using the new alveolar epithelial type I-like cell line R3/1 derived from fetal rat lung, we studied the distribution of connexin43 and caveolin-1 under conditions of bleomycin-induced injury in vitro. We show that under normal as well as under conditions of injury, endogenous connexin43 does not directly interact with endogenous caveolin-1 as revealed by immunofluorescence, glutathione S-transferase/caveolin-1 "pull down" assay, and co-immunoprecipitation experiments. The assessment of Triton X-100 solubility revealed that caveolin-1 was abundant in detergent-resistant membrane fractions. This is consistent with the localization of caveolin-1 in the lipid rafts/caveolae. Similarly, phosphorylated connexin43 was preferably detected in the Triton-insoluble fraction. Using a sucrose gradient we demonstrated that the majority of phosphorylated connexin43 colocalizes with caveolin-1 in lipid rafts, whereas all other forms of connexin43 remain in the bulk of cellular membranes and cytosolic proteins. Triton solubility assessment of bleomycin-treated cells revealed no differences in the caveolin-1 and connexin43 distribution. A further interesting outcome of our study is the shift of caveolin-1 from the lipid raft/caveolae fractions to the non-caveolar fractions after bleomycin treatment indicating an intracellular retention of caveolin-1. This result suggests the possibility that the translocation of caveolin-1 could be an important event regulating the metabolism of alveolar epithelial lung cells after injury.
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Affiliation(s)
- K Barth
- Institute of Anatomy, Medical Faculty Carl Gustav Carus, Dresden University of Technology, Fiedlerstrasse 42, 01307 Dresden, Germany
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Azzam EI, de Toledo SM, Little JB. Oxidative metabolism, gap junctions and the ionizing radiation-induced bystander effect. Oncogene 2003; 22:7050-7. [PMID: 14557810 DOI: 10.1038/sj.onc.1206961] [Citation(s) in RCA: 239] [Impact Index Per Article: 11.4] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/11/2022]
Abstract
Evidence accumulated over the past two decades has indicated that exposure of cell populations to ionizing radiation results in significant biological effects occurring in both the irradiated and nonirradiated cells in the population. This phenomenon, termed the 'bystander response', has been shown to occur both in vitro and in vivo and has been postulated to impact both the estimation of risks of exposure to low doses/low fluences of ionizing radiation and radiotherapy. Several mechanisms involving secreted soluble factors, oxidative metabolism and gap-junction intercellular communication have been proposed to regulate the radiation-induced bystander effect. Our current knowledge of the biochemical and molecular events involved in the latter two processes is reviewed in this article.
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Affiliation(s)
- Edouard I Azzam
- Department of Radiology, UMDNJ, New Jersey Medical School, Newark, NJ 07103,
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28
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Koval M. Sharing signals: connecting lung epithelial cells with gap junction channels. Am J Physiol Lung Cell Mol Physiol 2002; 283:L875-93. [PMID: 12376339 DOI: 10.1152/ajplung.00078.2002] [Citation(s) in RCA: 50] [Impact Index Per Article: 2.3] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/22/2022] Open
Abstract
Gap junction channels enable the direct flow of signaling molecules and metabolites between cells. Alveolar epithelial cells show great variability in the expression of gap junction proteins (connexins) as a function of cell phenotype and cell state. Differential connexin expression and control by alveolar epithelial cells have the potential to enable these cells to regulate the extent of intercellular coupling in response to cell stress and to regulate surfactant secretion. However, defining the precise signals transmitted through gap junction channels and the cross talk between gap junctions and other signaling pathways has proven difficult. Insights from what is known about roles for gap junctions in other systems in the context of the connexin expression pattern by lung cells can be used to predict potential roles for gap junctional communication between alveolar epithelial cells.
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Affiliation(s)
- Michael Koval
- Department of Physiology and Institute for Environmental Medicine, University of Pennsylvania School of Medicine, Philadelphia, Pennsylvania 19104, USA.
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Abraham V, Chou ML, George P, Pooler P, Zaman A, Savani RC, Koval M. Heterocellular gap junctional communication between alveolar epithelial cells. Am J Physiol Lung Cell Mol Physiol 2001; 280:L1085-93. [PMID: 11350787 DOI: 10.1152/ajplung.2001.280.6.l1085] [Citation(s) in RCA: 46] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/22/2022] Open
Abstract
We analyzed the pattern of gap junction protein (connexin) expression in vivo by indirect immunofluorescence. In normal rat lung sections, connexin (Cx)32 was expressed by type II cells, whereas Cx43 was more ubiquitously expressed and Cx46 was expressed by occasional alveolar epithelial cells. In response to bleomycin-induced lung injury, Cx46 was upregulated by alveolar epithelial cells, whereas Cx32 and Cx43 expression were largely unchanged. Given that Cx46 may form gap junction channels with either Cx43 or Cx32, we examined the ability of primary alveolar epithelial cells cultured for 6 days, which express Cx43 and Cx46, to form heterocellular gap junctions with cells expressing other connexins. Day 6 alveolar epithelial cells formed functional gap junctions with other day 6 cells or with HeLa cells transfected with Cx43 (HeLa/Cx43), but they did not communicate with HeLa/Cx32 cells. Furthermore, day 6 alveolar epithelial cells formed functional gap junction channels with freshly isolated type II cells. Taken together, these data are consistent with the notion that type I and type II alveolar epithelial cells communicate through gap junctions compatible with Cx43.
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Affiliation(s)
- V Abraham
- Department of Physiology, Institute for Environmental Medicine, University of Pennsylvania School of Medicine, 3620 Hamilton Walk, Philadelphia, PA 19104, USA
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30
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Alford AI, Rannels DE. Extracellular matrix fibronectin alters connexin43 expression by alveolar epithelial cells. Am J Physiol Lung Cell Mol Physiol 2001; 280:L680-8. [PMID: 11238008 DOI: 10.1152/ajplung.2001.280.4.l680] [Citation(s) in RCA: 21] [Impact Index Per Article: 0.9] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/22/2022] Open
Abstract
Alveolar type II epithelial cells undergo phenotypic changes and establish gap junction intercellular communication as they reach confluence in primary culture. The pattern of gap junction protein (connexin) expression changes in parallel. Although connexin (Cx)43 mRNA and protein increase significantly by culture day 2, Cx26 and Cx32 expression decline. Along with increasing Cx43 expression, the cells assemble fibronectin derived both from serum in the culture medium and from de novo synthesis into the extracellular matrix (ECM). The present studies indicate that this ECM regulates Cx43 expression. Culture of type II cells in DMEM containing 8-10% fetal bovine serum (FBS) promotes assembly of a fibronectin-rich ECM that stimulates expression of both Cx43 mRNA and protein. Although Cx43 protein expression increased in response to FBS in a dose-dependent manner, fibronectin also elevated Cx43 protein in the absence of FBS. Anti-fibronectin antibody significantly reduced the serum-dependent increase in Cx43 expression. These results support the premise that fibronectin in the ECM contributes to the regulation of Cx43 expression by alveolar epithelial cells in primary culture.
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Affiliation(s)
- A I Alford
- Department of Cellular and Molecular Physiology, The Pennsylvania State University College of Medicine, 500 University Dr., Hershey, PA 17033, USA
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Isakson BE, Evans WH, Boitano S. Intercellular Ca2+ signaling in alveolar epithelial cells through gap junctions and by extracellular ATP. Am J Physiol Lung Cell Mol Physiol 2001; 280:L221-8. [PMID: 11159000 DOI: 10.1152/ajplung.2001.280.2.l221] [Citation(s) in RCA: 75] [Impact Index Per Article: 3.3] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/22/2022] Open
Abstract
Inter- and extracellular-mediated changes in intracellular Ca2+ concentration ([Ca2+]i) can ensure coordinated tissue function in the lung. Cultured rat alveolar epithelial cells (AECs) have been shown to respond to secretagogues with increases in [Ca2+]i and have been shown to be gap junctionally coupled. However, communication of [Ca2+]i changes in AECs is not well defined. Monolayers of AECs were mechanically perturbed and monitored for [Ca2+]i changes. Perturbation of AECs was administered by a glass probe to either mechanically stimulate or mechanically wound individual cells. Both approaches induced a change in [Ca2+]i in the stimulated cell that was propagated to neighboring cells (Ca2+ waves). A connexin mimetic peptide shown to uncouple gap junctions eliminated Ca2+ waves in mechanically stimulated cells but had no effect on mechanically wounded cells. In contrast, apyrase, an enzyme that effectively removes ATP from the extracellular milieu, had no effect on mechanically stimulated cells but severely restricted mechanically wounded Ca2+ wave propagation. We conclude that AECs have the ability to communicate coordinated Ca2+ changes using both gap junctions and extracellular ATP.
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Affiliation(s)
- B E Isakson
- Department of Zoology and Physiology, University of Wyoming, Laramie, Wyoming 82071-3166, USA
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Fehrenbach H. Alveolar epithelial type II cell: defender of the alveolus revisited. Respir Res 2001; 2:33-46. [PMID: 11686863 PMCID: PMC59567 DOI: 10.1186/rr36] [Citation(s) in RCA: 519] [Impact Index Per Article: 22.6] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/27/2000] [Revised: 12/05/2000] [Accepted: 12/06/2000] [Indexed: 01/13/2023] Open
Abstract
In 1977, Mason and Williams developed the concept of the alveolar epithelial type II (AE2) cell as a defender of the alveolus. It is well known that AE2 cells synthesise, secrete, and recycle all components of the surfactant that regulates alveolar surface tension in mammalian lungs. AE2 cells influence extracellular surfactant transformation by regulating, for example, pH and [Ca2+] of the hypophase. AE2 cells play various roles in alveolar fluid balance, coagulation/fibrinolysis, and host defence. AE2 cells proliferate, differentiate into AE1 cells, and remove apoptotic AE2 cells by phagocytosis, thus contributing to epithelial repair. AE2 cells may act as immunoregulatory cells. AE2 cells interact with resident and mobile cells, either directly by membrane contact or indirectly via cytokines/growth factors and their receptors, thus representing an integrative unit within the alveolus. Although most data support the concept, the controversy about the character of hyperplastic AE2 cells, reported to synthesise profibrotic factors, proscribes drawing a definite conclusion today.
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Affiliation(s)
- H Fehrenbach
- Institute of Pathology, University Clinics Carl Gustav Carus, Technical University of Dresden, Germany.
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Wiszniewski L, Limat A, Saurat JH, Meda P, Salomon D. Differential expression of connexins during stratification of human keratinocytes. J Invest Dermatol 2000; 115:278-85. [PMID: 10951247 DOI: 10.1046/j.1523-1747.2000.00043.x] [Citation(s) in RCA: 59] [Impact Index Per Article: 2.5] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/20/2022]
Abstract
To assess whether gap junctions and connexins change during keratinocyte differentiation, we have studied epidermal equivalents obtained in organotypic cultures of keratinocytes from the outer root sheath of human hair follicles. These reconstituted tissues exhibit a number of differentiation and proliferation markers of human epidermis, including gap junctions, connexins, and K6 and Ki67 proteins. Immunostaining and northern blots showed that gap junctions of the epidermal equivalents were made of Cx26 and Cx43. Cx26 was expressed in all keratinocyte layers, throughout the development of the epidermal equivalents. In contrast, Cx43 was initially observed only in the basal layer of keratinocytes and became detectable in the stratum spinosum and granulosum only after the epidermal equivalents had thickened. The levels of Cx26 and its transcript markedly increased as a function of stratification of the epidermal equivalents, whereas those of Cx43 remained almost constant. Microinjection of Lucifer Yellow into individual keratinocytes showed that gap junctions were similarly permeable at all stages of development of the epidermal equivalents. The data show that epidermal equivalents (i) feature a pattern of connexins typical of an actively renewing human interfollicular epidermis, and (ii) provide a model that reproduces the tridimensional organization of intact epidermis and that is amenable for experimentally testing the function of junctional communication between human keratinocytes.
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Affiliation(s)
- L Wiszniewski
- Departments of Dermatology (DHURDV) and Morphology, University of Geneva, Switzerland
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Abstract
Cultured dermal fibroblasts become notably elongated when incorporated into a fibroblast-populated collagen lattice (FPCL). With time these fibroblasts reorganize the collagen responsible for reduction in lattice size. In monolayer the microinjection of Lucifer Yellow (LY) into cultured human fibroblasts shows cell coupling through gap junctions. Human fibroblasts residing on the periphery of a FPCL are at high density and the microinjection of LY into one of those fibroblasts demonstrates cell coupling. Cells within the center of an FPCL are at low density and appear to be independent of one another; however, the microinjection of LY into selected fibroblasts again demonstrates cell coupling. Hence the microinjection of cells in both the center and the edge of a FPCL pass dye to numerous neighbors. Does cell coupling influence FPCL contraction? FPCL incubated with heptanol and octanol, aliphatic alcohols that uncouple cells, inhibits lattice contraction, whereas hexanol, an aliphatic alcohol that does not uncouple cells, did not alter lattice contraction. Fibroblasts derived from connexin 43 (a transmembrane protein responsible for gap junction structures) knockout mice were demonstrated to lack gap junctional communications. When incorporated into a FPCL these cells failed to elongate and demonstrated retarded lattice contraction. Hence, gap junctional communications between fibroblasts incorporated into collagen lattices appear to optimize FPCL contraction and suggest a role for gap junctions in the organization of collagen fibers.
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Affiliation(s)
- H P Ehrlich
- Division of Plastic and Reconstructive Surgery, Milton S. Hershey Medical Center, Hershey, Pennsylvania, USA.
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Guo Y, Martinez-Williams C, Gilbert KA, Rannels DE. Inhibition of gap junction communication in alveolar epithelial cells by 18alpha-glycyrrhetinic acid. THE AMERICAN JOURNAL OF PHYSIOLOGY 1999; 276:L1018-26. [PMID: 10362727 DOI: 10.1152/ajplung.1999.276.6.l1018] [Citation(s) in RCA: 45] [Impact Index Per Article: 1.8] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 11/22/2022]
Abstract
Cultured alveolar epithelial cells exhibit gap junction intercellular communication (GJIC) and express regulated levels of connexin (Cx) 43 mRNA and protein. Newly synthesized radiolabeled Cx43 protein equilibrates with phosphorylated Cx43 isoforms; these species assemble to form both connexons and functional gap junction plaques. The saponin 18alpha-glycyrrhetinic acid (GA) rapidly and reversibly blocks GJIC at low concentrations (5 microM). Extended exposure to 18alpha-GA at higher concentrations causes inhibition of GJIC and time- and dose-dependent reductions in both Cx43 protein and mRNA expression. The latter toxic effects are paralleled by disassembly of gap junction plaques and are reversed less readily than acute effects on GJIC. These observations demonstrate 18alpha-GA-sensitive regulation of intercellular communication in epithelial cells from the mammalian lung and suggest a role for Cx43 expression and phosphorylation in acute and chronic regulation of GJIC between alveolar epithelial cells.
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Affiliation(s)
- Y Guo
- Department of Cellular and Molecular Physiology, The Pennsylvania State University College of Medicine, Hershey, Pennsylvania 17033, USA
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Abraham V, Chou ML, DeBolt KM, Koval M. Phenotypic control of gap junctional communication by cultured alveolar epithelial cells. THE AMERICAN JOURNAL OF PHYSIOLOGY 1999; 276:L825-34. [PMID: 10330039 DOI: 10.1152/ajplung.1999.276.5.l825] [Citation(s) in RCA: 45] [Impact Index Per Article: 1.8] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 11/22/2022]
Abstract
We examined phenotype-specific changes in gap junction protein [connexin (Cx)] expression and function by cultured rat alveolar type II cells. Type II cells cultured on extracellular matrix in medium containing keratinocyte growth factor (KGF) and 2% fetal bovine serum (FBS; KGF/2) retained expression of surfactant protein C and the 180-kDa lamellar body membrane protein (lbm180). These markers were lost when cells were cultured in medium containing 10% FBS (MEM/10). With RT-PCR, cells cultured in MEM/10 showed transient increases in Cx43 and Cx46 mRNA expression, whereas Cx32 and Cx26 decreased and Cx30.3 and Cx37 were unchanged. Transient changes in Cx32, Cx43, and Cx46 protein expression were confirmed by immunoblot. In contrast, cells cultured in KGF/2 retained expression of Cx32 and showed increased expression of Cx30.3 and Cx46 mRNAs, compared with that in day 0 cells. With immunofluorescence microscopy, Cx32 and Cx43 were at the plasma membrane of cells grown in KGF/2, whereas Cx46 was exclusively intracellular. Type II cells cultured in MEM/10 showed approximately 3- to 4-fold more intercellular transfer of microinjected lucifer yellow through gap junctions than cells grown in 2% FBS. Thus type II cells dynamically alter gap junctional communication, and distinct alveolar epithelial cell phenotypes express different connexins.
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Affiliation(s)
- V Abraham
- Department of Physiology and Institute for Environmental Medicine, University of Pennsylvania School of Medicine, Philadelphia, Pennsylvania 19104, USA
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